Bioinspired synthesis of polyzwitterion/titania functionalized carbon nanotube membrane with superwetting property for efficient oil-in-water emulsion separation

Oil/water separation membranes with high flux efficiency and robust anti-oil-fouling property have attracted numerous attention, and superwetting carbon nanotube (CNT) membranes are promising candidates. The key challenges focus on the versatile integration of multiple materials/structures and the facile functionalization towards superhydrophilicity/underwater superoleophobicity. In this study, a polyzwitterion/titania functionalized carbon nanotube membrane for antifouling and high-flux oil/water emulsion separation is synthesized by a novel and simple dual-bioinspired strategy. The strategy involves the co-assembly of polyzwitterion and bioinspired-adhesive polydopamine (PDA) modified CNTs and the bioinspired mineralization of titania nanoparticles (TNPs). The as-prepared CNT membrane is evenly decorated with polyzwitterion and TNPs mediated by the comprehensive adhesive capability of PDA. The integration of the hydrophilic advantages of polyzwitterion and titania and the integration of the multiscale structures of CNTs and TNPs endow membranes with superhydrophilicity, underwater superoleophobicity and anti-oil-adhesion property. The nanoscale porous structures of CNT assembled network ensure the high permeability (about 3400 L m(-2)h(-1)) and separation efficiency (over 99.5% for emulsified oils) of membranes. Furthermore, when applied to oil-in-water emulsion separation, the as-prepared CNT membrane exhibits good recycle performance throughout several filtration cycles and maintains high recovery ratio of 95% after several cycles, indicating excellent antifouling property. The dual-bioinspired strategy combining bioinspired adhesion and bioinspired mineralization provides new insights into the design and construction of nano-structured membranes for oil/water separation.